This invention relates to a surface flow head. More specifically, but not by way of limitation, this invention relates to a flow valve and method used on the surface of oil and gas installations such as drilling rigs and production platforms.
In the course of drilling, completing, and producing subterranean reservoirs, operators find it necessary to rig up and run into a well various types of work strings. Examples of work strings include, but not limited to, drill strings, coiled tubing, snubbing pipe, and wireline. As those of ordinary skill in the art will recognize, operators will perform various types of well intervention operations on rigs and platforms. The pressure of subterranean reservoirs may be several thousand pounds per square inch (psi). Operators are always concerned with safety of the crew and the rig. Hence, during any type of operation, operators will employ various types of valves that will control the pressure at the surface.
For instance, the specific operation may be to run coiled tubing into a well on a floating platform. A blow out preventer stack (BOP stack) may be rigged to the well at the surface, and wherein the BOP stack will function to surround the coiled tubing to prevent any escape of pressure from subterranean reservoir via the annulus. A lubricator type of string connects to the BOP stack, and wherein the lubricator allows for the entry of the worksting into the well. Additionally, operators will also place a valve that is made up with the lubricator so that pressure that is within the work string can be contained and controlled.
In the past, valves such as the Texas Iron Works, known in the industry as the TIW valve were used. The TIW valves are essentially ball valves that seal in both directions. Other valves have been developed over the years that are similar to the TIW valve. For instance, there is a valve that has become known as a lower kelly valve, and wherein these valves are shorter, in a single piece, and contain an actuating mechanism that is recessed. The lower kelly valves are commercially available from Hydril Inc. under the name lower kelly valve. Hence, as part of the lubricator may contain a lower kelly valve to control the pressures within the inner portion of the lubricator.
However, these valve systems suffer from several disadvantages. For instance, it is desirable to be able to allow flow from the well, but still be able to keep control of the well. Also, the prior art does not allow for a safe and efficient system to pump into the well. Additionally, these prior art systems do not allow the ability to rotate below the valve, while maintaining the valve stationary when attempting to land a tubing hanger. Also, in cases of rigging up, rigging down or performing some other type of maintenance to the BOP stack, or well intervention string, etc, the operator has the ability to rotate either the top half or the bottom half of the valve assembly, while keeping the opposite half stationary. These needs, and many others, will be met by the following described invention.